Free public beta until December 4, 2026: every course is open, no card needed. After that, the first chapter of each course stays free and full access is a one-time $39 ($19 for up to 100 founding members chosen for helpful feedback). Your progress is kept. How the beta works

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Isomorphism Recognition Survival

Z_m x Z_n vs Z_mn -- matching order alone never proves isomorphic, only gcd(m,n)=1 does. One wrong verdict ends the round.

💀 3 lifeives 🚫 no clock

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